using System;
using System.Collections.Generic;

namespace Chronos.Extensions
{
    /// <summary>
    /// Extension methods for all kind of Lists implementing the IList&lt;T&gt; interface
    /// </summary>
    public static class ListExtensions
    {
        #region · Extensions ·

        /// <summary>
        /// Inserts an item uniquely to to a list and returns a value whether the item was inserted or not.
        /// </summary>
        /// <typeparam name="T">The generic list item type.</typeparam>
        /// <param name="list">The list to be inserted into.</param>
        /// <param name="index">The index to insert the item at.</param>
        /// <param name="item">The item to be added.</param>
        /// <returns>Indicates whether the item was inserted or not</returns>
        public static bool InsertUnqiue<T>(this IList<T> list, int index, T item)
        {
            if (list.Contains(item) == false)
            {
                list.Insert(index, item);
                return true;
            }

            return false;
        }

        /// <summary>
        /// Inserts a range of items uniquely to a list starting at a given index and returns the amount of items inserted.
        /// </summary>
        /// <typeparam name="T">The generic list item type.</typeparam>
        /// <param name="list">The list to be inserted into.</param>
        /// <param name="startIndex">The start index.</param>
        /// <param name="items">The items to be inserted.</param>
        /// <returns>The amount if items that were inserted.</returns>
        public static int InsertRangeUnique<T>(this IList<T> list, int startIndex, IEnumerable<T> items)
        {
            var index = startIndex;

            foreach (var item in items)
            {
                if (list.InsertUnqiue(startIndex, item))
                {
                    index++;
                }
            }

            return (index - startIndex);
        }

        /// <summary>
        /// Return the index of the first matching item or -1.
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="list">The list.</param>
        /// <param name="comparison">The comparison.</param>
        /// <returns>The item index</returns>
        public static int IndexOf<T>(this IList<T> list, Func<T, bool> comparison)
        {
            for (var i = 0; i < list.Count; i++)
            {
                if (comparison(list[i]))
                {
                    return i;
                }
            }

            return -1;
        }

        #endregion
    }
}